The present invention relates to novel 3-benzoyl-2-mercaptopropionic acid derivatives, and more particularly, it relates to 3-benzoyl-2-mercaptopropionic acid derivatives which have immunomodulative function and are effective for treatment of diseases caused by abnormal immunofunction.
In the past, there have been used the so-called immunosuppressors for treatment of autoimmune diseases such as chronic rheumatoid arthritis. In general, however, the suppressive activity of the agents is mainly based on cytotoxicity. Accordingly, because of a strong side-effect depending on the above-mentioned cytotoxicity, these agents can not be said to be appropriate as therapeutical agents of autoimmune diseases which are required to be administered continuously for a long term.
Further, in order to treat diseases related to immune, there have been recently used the so-called immunomodulators which have the effect to regulate the immune function, i.e., either stimulate the immune function when lowered, or suppress the immune function when augmented. However, even these agents cannot be said to be satisfactory in aspects of effect, side-effect and toxicity.
As a result of the ernest studies, the present inventors have found that certain 3-benzoyl-2-mercaptopropionic acid derivatives have good immunomodulative function, weak side-effect and weak toxicity, and thus the present invention has been completed.